Exercise analysis device, exercise analysis method, program, recording medium, and exercise analysis system

ABSTRACT

A first imaginary plane specifying unit specifies a first axis which lies in a longitudinal direction of a shaft of an exercise tool at an address posture of a user, using an output of an inertial sensor. A second imaginary plane specifying unit specifies a second axis forming a predetermined angle along with the first axis, using a hitting direction as a rotation axis. An exercise analysis unit calculates a trajectory of a swing of the user based on an output of the inertial sensor. A trajectory determination unit determines whether the trajectory of the swing passes through a predetermined region specified based on the first and second axes.

BACKGROUND

1. Technical Field

The present invention relates to an exercise analysis device, anexercise analysis method, a program, a recording medium, and an exerciseanalysis system.

2. Related Art

JP-A-2010-82430 discloses that an image is acquired by performingphotographing from the rear side in a hitting direction between anaddress state to the end of a swing and the image is split into at leastthree regions by a first straight line passing through a shaft axis of agolf club in the address state and a second straight line intersectingthe first straight line and passing through the root of an installed teeand the base of the neck of a golfer.

However, a V zone is known as an index for indicating goodness andbadness of a swing. In general, when a trajectory of a swing is includedin a V zone, the swing is estimated to be a good swing.

In JP-A-2010-82430, a golfer at the time of address is photographed fromthe rear side of the hitting direction using a camera and, for example,a user draws a line in the photographed image to specify a V zone. InJP-A-2010-82430, the golfer performing a swing is photographed using acamera and it is visually confirmed whether a trajectory of the swing ofthe golfer is contained in the V zone drawn by the user. Therefore, inJP-A-2010-82430, there is a problem that it is difficult to estimate aswing.

SUMMARY

An advantage of some aspects of the invention is that it provides atechnology for simply estimating a swing.

A first aspect of the invention is directed to an exercise analysisdevice including: a first specifying unit that specifies a first axiswhich lies in a longitudinal direction of a shaft of an exercise tool atan address posture of a user, using an output of an inertial sensor; asecond specifying unit that specifies a second axis forming apredetermined angle along with the first axis, using a hitting directionas a rotation axis; an analysis unit that calculates a trajectory of aswing of the user based on an output of the inertial sensor; and adetermination unit that determines whether the trajectory passes througha predetermined region specified based on the first and second axes.

According to the first aspect of the invention, the exercise analysisdevice can change the display form of the trajectory of the swingaccording to the passage state of the trajectory of the swing throughthe predetermined region specified based on the first and second axes.Thus, the user can easily see whether the trajectory of a swing passesthrough the predetermined region specified based on the first and secondaxes, and thus can simply perform a swing estimation.

The determination unit may determine a portion of the trajectory whichpasses through the predetermined region and a portion of the trajectorywhich does not pass through the predetermined region.

With this configuration, the exercise analysis device can change thedisplay form of the trajectory of the swing in the portion of thetrajectory of the swing which passes through the predetermined regionand the portion of the trajectory of the swing which does not passthrough the predetermined region. The user can easily see whether thetrajectory of a swing passes through the predetermined region specifiedbased on the first and second axes, and thus can simply perform theswing estimation.

The exercise analysis device may further include an image generationunit that generates image data in which a display form of the trajectorydiffers between the portion which passes through the predeterminedregion and the portion which does not pass through the predeterminedregion.

With this configuration, in accordance with the difference in thedisplay from of the trajectory of the swing, the user can easily seewhether the trajectory of the swing passes through the predeterminedregion specified based on the first and second axes, and thus can simplyperform the swing estimation.

The image generation unit may generate the image data in which a colorof the trajectory differs between the portion which passes through thepredetermined region and the portion which does not pass through thepredetermined region.

With this configuration, in accordance with the difference in the colorof the trajectory of the swing, the user can easily see whether thetrajectory of the swing passes through the predetermined regionspecified based on the first and second axes, and thus can simplyperform the swing estimation.

The image generation unit may generate the image data in which thetrajectory continuously lights and blinks to distinguish the portionwhich passes through the predetermined region from the portion whichdoes not pass through the predetermined region.

With this configuration, in accordance with the continuous lighting orblinking of the trajectory of the swing, the user can easily see whetherthe trajectory of the swing passes through the predetermined regionspecified based on the first and second axes, and thus can simplyperform the swing estimation.

The image generation unit may generate the image data in which a kind ofline of the trajectory differs between the portion which passes throughthe predetermined region and the portion which does not pass through thepredetermined region.

With this configuration, in accordance with the difference in the kindof the trajectory of the swing, the user can easily see whether thetrajectory of the swing passes through the predetermined regionspecified based on the first and second axes, and thus can simplyperform the swing estimation.

The image generation unit may generate the image data in which athickness of a line of the trajectory differs between the portion whichpasses through the predetermined region and the portion which does notpass through the predetermined region.

With this configuration, in accordance with the difference in thethickness of the line of the trajectory of the swing, the user caneasily see whether the trajectory of the swing passes through thepredetermined region specified based on the first and second axes, andthus can simply perform the swing estimation.

The first specifying unit may specify a first imaginary plane includingthe first axis and the hitting direction. The second specifying unit mayspecify a second imaginary plane including the second axis and thehitting direction. The predetermined region may be a region interposedbetween the first and second imaginary planes.

With this configuration, the user can easily see whether the trajectoryof the swing passes through the predetermined region interposed betweenthe first and second imaginary planes, and thus can simply perform theswing estimation.

The image generation unit may define first and second regionsinterposing the predetermined region outside the predetermined region,and generate image data in which the predetermined region, the firstregion, and the second region are distinguished and displayed.

With this configuration, the user can easily see how the trajectory ofthe swing passes through the first and second regions, and thus cansimply perform the swing estimation.

A second aspect of the invention is directed to an exercise analysismethod including: specifying a first axis which lies in a longitudinaldirection of a shaft of an exercise tool at an address posture of auser, using an output of an inertial sensor; specifying a second axisforming a predetermined angle along with the first axis, using a hittingdirection as a rotation axis; calculating a trajectory of a swing of theuser based on an output of the inertial sensor; and determining whetherthe trajectory passes through a predetermined region specified based onthe first and second axes.

According to the second aspect of the invention, the exercise analysisdevice can change the display form of the trajectory of the swingaccording to the passage state of the trajectory of the swing throughthe predetermined region specified based on the first and second axes.Thus, the user can easily see whether the trajectory of a swing passesthrough the predetermined region specified based on the first and secondaxes, and thus can simply perform the swing estimation.

In the determining of the trajectory, a portion of the trajectory whichpasses through the predetermined region and a portion of the trajectorywhich does not pass through the predetermined region may be determined.

Thus, in the exercise analysis method, the display form of thetrajectory of the swing can be changed in the portion of the trajectoryof the swing which passes through the predetermined region and theportion of the trajectory of the swing which does not pass through thepredetermined region. The user can easily see whether the trajectory ofa swing passes through the predetermined region specified based on thefirst and second axes, and thus can simply perform the swing estimation.

A third aspect of the invention is directed to a program causing acomputer to perform: specifying a first axis which lies in alongitudinal direction of a shaft of an exercise tool at an addressposture of a user, using an output of an inertial sensor; specifying asecond axis forming a predetermined angle along with the first axis,using a hitting direction as a rotation axis; calculating a trajectoryof a swing of the user based on an output of the inertial sensor; anddetermining whether the trajectory passes through a predetermined regionspecified based on the first and second axes.

According to the third aspect of the invention, the computer can changethe display form of the trajectory of the swing according to the passagestate of the trajectory of the swing through the predetermined regionspecified based on the first and second axes. Thus, the user can easilysee whether the trajectory of a swing passes through the predeterminedregion specified based on the first and second axes, and thus can simplyperform the swing estimation.

Another aspect of the invention is directed to a recording medium thatrecords a program causing a computer to perform: specifying a first axiswhich lies in a longitudinal direction of a shaft of an exercise tool atan address posture of a user, using an output of an inertial sensor;specifying a second axis forming a predetermined angle along with thefirst axis, using a hitting direction as a rotation axis; calculating atrajectory of a swing of the user based on an output of the inertialsensor; and determining whether the trajectory passes through apredetermined region specified based on the first and second axes.

According to the another aspect of the invention, the computer canchange the display form of the trajectory of the swing according to thepassage state of the trajectory of the swing through the predeterminedregion specified based on the first and second axes. Thus, the user caneasily see whether the trajectory of a swing passes through thepredetermined region specified based on the first and second axes, andthus can simply perform the swing estimation.

A fourth aspect of the invention is directed to an exercise analysissystem including: an inertial sensor; a first specifying unit thatspecifies a first axis which lies in a longitudinal direction of a shaftof an exercise tool at an address posture of a user, using an output ofthe inertial sensor; a second specifying unit that specifies a secondaxis forming a predetermined angle along with the first axis, using ahitting direction as a rotation axis; an analysis unit that calculates atrajectory of a swing of the user based on an output of the inertialsensor; and a determination unit that determines whether the trajectorypasses through a predetermined region specified based on the first andsecond axes.

According to the fourth aspect of the invention, the exercise analysissystem can change the display form of the trajectory of the swingaccording to the passage state of the trajectory of the swing throughthe predetermined region specified based on the first and second axes.Thus, the user can easily see whether the trajectory of a swing passesthrough the predetermined region specified based on the first and secondaxes, and thus can simply perform the swing estimation.

Still another aspect of the invention is directed to an exerciseanalysis device that determines whether a trajectory of a swing of auser passes through a V zone.

A display form of the trajectory may differ between a portion of thetrajectory which passes through the V zone and a portion of thetrajectory which does not pass through the V zone.

The exercise analysis device may further include an image generationunit that generates image data in which the display form of thetrajectory differs between the portion which passes through thepredetermined region and the portion which does not pass through thepredetermined region.

The image generation unit may generate image data in which a color ofthe trajectory differs between the portion which passes through thepredetermined region and the portion which does not pass through thepredetermined region.

The image generation unit may generate image data in which thetrajectory continuously lights and blinks to distinguish the portionwhich passes through the predetermined region from the portion whichdoes not pass through the predetermined region.

The image generation unit may generate image data in which a kind ofline of the trajectory differs between the portion which passes throughthe predetermined region and the portion which does not pass through thepredetermined region.

The image generation unit may generate image data in which a thicknessof line of the trajectory differs between the portion which passesthrough the predetermined region and the portion which does not passthrough the predetermined region.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a diagram illustrating an overview of an exercise analysissystem according to an embodiment of the invention.

FIG. 2 is a diagram illustrating examples of a shaft plane and a Hogan'splane.

FIG. 3 is a block diagram illustrating an example of the configurationof an exercise analysis system.

FIG. 4 is a flowchart illustrating an example of an exercise analysisprocess.

FIG. 5 is a plan view illustrating a golf club and a sensor unit at thetime of stopping of a user when viewed from the negative side of the Xaxis.

FIG. 6 is a diagram illustrating a cross section obtained by cutting theshaft plane along the YZ plane when viewed from the negative side of theX axis.

FIG. 7 is a diagram illustrating a cross section obtained by cutting theHogan's plane along the YZ plane when viewed from the negative side ofthe X axis.

FIG. 8 is a diagram illustrating examples of angular velocities outputfrom the sensor unit.

FIG. 9 is a diagram illustrating an example of a norm of an angularvelocity.

FIG. 10 is a diagram illustrating an example of a differential value ofthe norm of an angular velocity.

FIG. 11 is a diagram (a diagram projected to the YZ plane) illustratingthe shaft plane and the Hogan's plane when viewed from the negative sideof the X axis.

FIG. 12 is a diagram illustrating an example of a screen displayed on adisplay unit.

FIG. 13 is a flowchart illustrating an example of operations of atrajectory determination unit and an image generation unit.

FIG. 14 is a diagram illustrating an example of a screen in which aregion outside a V zone including a line segment and a Hogan's plane isdisplayed.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, embodiments of the invention will be described withreference to the drawings. Hereinafter, an exercise analysis systemperforming analysis of a golf swing will be described as an example.

FIG. 1 is a diagram illustrating an overview of an exercise analysissystem according to an embodiment of the invention.

An exercise analysis system 1 includes a sensor unit 10 and an exerciseanalysis device 20.

The sensor unit 10 can measure acceleration generated in each axisdirection of three axes and an angular velocity generated in eachrotation of the three axes as an inertial sensor and is mounted on agolf club 3. For example, the sensor unit 10 is fitted on a part of theshaft of the golf club 3 when one axis among three detection axes (the xaxis, the y axis, and the z axis), for example, the y axis, conforms tothe major axis direction of the shaft. Preferably, the sensor unit 10 isfitted at a position close to a grip in which a shock at the time of ashot is rarely delivered and a centrifugal force is not applied at thetime of a swing. The shaft is a portion of the handle excluding the headof the golf club 3 and also includes the grip.

A user 2 performs a swing motion of hitting a golf ball (notillustrated) in a pre-decided procedure. For example, the user 2 firstholds the golf club 3, takes a posture of address so that the major axis(longitudinal direction) of the shaft of the golf club 3 is vertical toa target line (a hitting target direction), and stops for apredetermined time or more (for example, 1 second or more). Next, theuser 2 performs a swing motion to hit the golf ball. The posture ofaddress in the present specification includes a posture in a stop stateof the user before start of a swing or a posture in a state in which theuser shakes an exercise tool (waggling) before start of a swing. Thetarget line refers to any hitting direction and is decided as, forexample, a hitting target direction in the embodiment.

While the user 2 performs the motion to hit the golf ball in theabove-described procedure, the sensor unit 10 measures triaxialacceleration and triaxial angular velocities at a predetermined period(for example, 1 ms) and sequentially transmits the measurement data tothe exercise analysis device 20. The sensor unit 10 may immediatelytransmit the measurement data, or may store the measurement data in aninternal memory and transmit the measurement data at a desired timingsuch as the end of a swing motion of the user 2. Communication betweenthe sensor unit 10 and the exercise analysis device 20 may be wirelesscommunication or wired communication. Alternatively, the sensor unit 10may store the measurement data in a recording medium such as a memorycard which can be detachably mounted and the exercise analysis device 20may read the measurement data from the recording medium.

The exercise analysis device 20 analyzes a swing exercise performed withthe golf club 3 by the user 2 using the data measured by the sensor unit10. In particular, in the embodiment, the exercise analysis device 20specifies a shaft plane (which corresponds to a first imaginary plane ora first axis according to the invention) and a Hogan's plane (whichcorresponds to a second imaginary plane or a second axis according tothe invention) at the time of stopping of the user 2 (the time ofaddress) using the data measured by the sensor unit 10.

The exercise analysis device 20 calculates a trajectory of the golf club3 (for example, a trajectory of the head) at a swing after the user 2starts the swing motion. The exercise analysis device 20 changes adisplay form of the trajectory according to a passage state of thetrajectory of the golf club 3 through a region referred to as a V zonebetween the shaft plane and the Hogan's plane and displays the displayform of the trajectory on a display device. At this time, the exerciseanalysis device 20 does not display the shaft plane and the Hogan'splane indicating the V zone in the display device. That is, when theexercise analysis device 20 changes the display form of the trajectoryof the golf club 3 by displaying the display form in the display device,the user 2 sees how the trajectory of the golf club 3 passes through theV zone.

For example, the exercise analysis device 20 displays a trajectoryoutside the V zone with a first color such as red in the display deviceand displays a trajectory inside the V zone with a second color, such asblue, different from the first color in the display device. Thus, theuser 2 can see how the trajectory of his or her swing passes through theV zone even when the shaft plane and the Hogan's plane indicating the Vzone is not displayed in the display device.

The exercise analysis device 20 may be, for example, a portable devicesuch as a smartphone or a personal computer (PC). In FIG. 1, theexercise analysis device 20 is mounted on the waist of the user 2, butthe mounted position is not particularly limited. Further, the exerciseanalysis device 20 may not be mounted on the user 2.

FIG. 2 is a diagram illustrating examples of the shaft plane and theHogan's plane. In the embodiment, an XYZ coordinate system (globalcoordinate system) in which a target line indicating a hitting targetdirection is an X axis, an axis on a horizontal plane vertical to the Xaxis is a Y axis, and an upward vertical direction (which is an oppositedirection to the direction of the gravity acceleration) is a Z axis isdefined. In FIG. 2, the X, Y, and Z axes are shown.

A shaft plane 30 at the time of address of the user 2 is an imaginaryplane which includes a first line segment 51 serving as a first axiswhich lies in the major axis direction of the shaft of the golf club 3and a third line segment 52 serving as a third axis indicating a hittingtarget direction and has four vertexes T1, T2, S1, and S2. In theembodiment, a position 61 of the head (blow portion) of the golf club 3is set as the origin O (0, 0, 0) of the XYZ coordinate system. The firstline segment 51 is a line segment which connects the position 61 (theorigin O) of the head of the golf club 3 to a position 62 of a grip end.The third line segment 52 is a line segment which has T1 and T2 on the Xaxis as both ends, has a length TL, and centers on the origin O. Whenthe user 2 takes the above-described address posture at the time of theaddress, the shaft of the golf club 3 is vertical to the target line(the X axis). Therefore, the third line segment 52 is a line segmentwhich is perpendicular to the major axis direction of the shaft of thegolf club 3, that is, a line segment perpendicular to the first linesegment 51. The shaft plane 30 is specified by calculating thecoordinates of the four vertexes T1, T2, S1, and S2 in the XYZcoordinate system. A method of calculating the coordinates of the fourvertexes T1, T2, S1, and S2 will be described in detail below.

The Hogan's plane 40 is an imaginary plane which includes the third linesegment 52 and a second line segment 53 serving as a second axis and hasfour vertexes T1, T2, H1, and H2. In the embodiment, the second linesegment 53 is a line segment which connects the position 62 (which is anexample of a blow position) of the head (which is a blow portion) of thegolf club 3 to a predetermined position 63 (which is, for example, theposition of the base of the neck or the position of one of the right andleft shoulders) on a line segment connecting both shoulders of the user2 to one another. Here the second line segment 53 may be a line segmentwhich connects the predetermined position 63 to the position (which isan example of the blow position) of a ball at the time of address. AHogan's plane 40 is specified by calculating the coordinates of the fourvertexes T1, T2, H1, and H2 in the XYZ coordinate system. A method ofcalculating the coordinates of the four vertexes T1, T2, H1, and H2 willbe described in detail below.

FIG. 3 is a block diagram illustrating an example of the configurationof an exercise analysis system.

The sensor unit 10 includes a control unit 11, a communication unit 12,an acceleration sensor 13, and an angular velocity sensor 14.

The acceleration sensor 13 measures acceleration generated in each ofmutually intersecting (ideally, orthogonal) triaxial directions andoutputs digital signals (acceleration data) according to the sizes anddirections of the measured triaxial accelerations.

The angular velocity sensor 14 measures an angular velocity generated ataxis rotation of mutually intersecting (ideally, orthogonal) three axesand outputs digital signals (angular velocity data) according to thesizes and directions of the measured triaxial angular velocities.

The control unit 11 controls the sensor unit in an integrated manner.The control unit 11 receives the acceleration data and the angularvelocity data from the acceleration sensor 13 and the angular velocitysensor 14, appends time information, and stores the acceleration dataand the angular velocity data in a storage unit (not illustrated). Thecontrol unit 11 generates packet data in conformity to a communicationformat by appending time information to the stored measurement data (theacceleration data and the angular velocity data) and outputs the packetdata to the communication unit 12.

The acceleration sensor 13 and the angular velocity sensor 14 areideally fitted in the sensor unit 10 so that the three axes of eachsensor match the three axes (the x axis, the y axis, and the z axis) ofthe rectangular coordinate system (sensor coordinate system) defined forthe sensor unit 10, but errors of the fitting angles actually occur.Accordingly, the control unit 11 performs a process of converting theacceleration data and the angular velocity data into data of the xyzcoordinate system, using correction parameters calculated in advanceaccording to the errors of the fitting angles.

The control unit 11 may perform a temperature correction process of theacceleration sensor 13 and the angular velocity sensor 14.Alternatively, a temperature correction function may be embedded in theacceleration sensor 13 and the angular velocity sensor 14.

The acceleration sensor 13 and the angular velocity sensor 14 may outputanalog signals. In this case, the control unit 11 may perform A/D(analog/digital) conversion on each of an output signal of theacceleration sensor 13 and an output signal of the angular velocitysensor 14, generate measurement data (acceleration data and angularvelocity data), and generate packet data for communication using themeasurement data.

The communication unit 12 performs, for example, a process oftransmitting the packet data received from the control unit 11 to theexercise analysis device 20 or a process of receiving control commandsfrom the exercise analysis device 20 and transmitting the controlcommands to the control unit 11. The control unit 11 performs variousprocesses according to the control commands.

The exercise analysis device 20 includes a control unit 21, acommunication unit 22, an operation unit 23, a storage unit 24, adisplay unit 25, and a sound output unit 26.

The communication unit 22 performs, for example, a process of receivingthe packet data transmitted from the sensor unit 10 and transmitting thepacket data to the control unit 21 or a process of transmitting acontrol command from the control unit 21 to the sensor unit 10.

The operation unit 23 performs a process of acquiring operation datafrom the user and transmitting the operation data to the control unit21. The operation unit 23 may be, for example, a touch panel typedisplay, a button, a key, or a microphone.

The storage unit 24 is configured by, for example, any of various ICmemories such as a read-only memory (ROM), a flash ROM, and a randomaccess memory (RAM) or a recording medium such as a hard disk or amemory card.

The storage unit 24 stores, for example, programs used for the controlunit 21 to perform various calculation processes or control processes,or various programs or data used for the control unit 21 to realizeapplication functions. In particular, in the embodiment, the storageunit 24 stores an exercise analysis program which is read by the controlunit 21 to perform an analysis process. The exercise analysis programmay be stored in advance in a nonvolatile recording medium.Alternatively, the exercise analysis program may be received from aserver via a network by the control unit 21 and may be stored in thestorage unit 24.

In the embodiment, the storage unit 24 stores body information of theuser 2, club specification information indicating the specification ofthe golf club 3, and sensor-mounted position information. For example,when the user 2 operates the operation unit 23 to input the bodyinformation such as a height, a weight, and a sex, the input bodyinformation is stored as body information in the storage unit 24. Forexample, the user 2 operates the operation unit 23 to input a modelnumber of the golf club 3 (or selects the model number from a modelnumber list) to be used and sets specification information regarding theinput model number as the club specification information among pieces ofspecification information for each model number (for example,information regarding the length of the shaft, the position of thecenter of gravity, a lie angle, a face angle, a loft angle, and thelike) stored in advance in the storage unit 24. For example, when theuser 2 operates the operation unit 23 to input a distance between theposition at which the sensor unit 10 is mounted and the grip end of thegolf club 3, information regarding the input distance is stored as thesensor-mounted position information in the storage unit 24.Alternatively, by mounting the sensor unit 10 at a decided predeterminedposition (for example, a distance of 20 cm from the grip end),information regarding the predetermined position may be stored inadvance as the sensor-mounted position information.

The storage unit 24 is used as a work area of the control unit 21 andtemporarily stores, for example, data input from the operation unit 23and calculation results performed according to various programs by thecontrol unit 21. The storage unit 24 may store data necessarily storedfor a long time among the data generated through the processes of thecontrol unit 21.

The display unit 25 displays a processing result of the control unit 21as text, a graph, a table, animations, or another image. The displayunit 25 may be, for example, a cathode ray tube (CRT) display, a liquidcrystal display (LCD), an electrophoretic display (EPD), a display usingan organic light-emitting diode (OLED), a touch panel type display, or ahead-mounted display (HMD). The functions of the operation unit 23 andthe display unit 25 may be realized by one touch panel type display.

The sound output unit 26 outputs a processing result of the control unit21 as audio such as a sound or a buzzer tone. The sound output unit 26may be, for example, a speaker or a buzzer.

The control unit 21 performs a process of transmitting a control commandto the sensor unit 10, various calculation processes on data receivedfrom the sensor unit 10 via the communication unit 22, and other variouscontrol processes according to various programs. In particular, in theembodiment, the control unit 21 executes an exercise analysis program tofunction as a sensor information acquisition unit 210, a first imaginaryplane specifying unit 211 (which corresponds to a first specifying unitaccording to the invention), a second imaginary plane specifying unit212 (which corresponds to a second specifying unit according to theinvention), an exercise analysis unit 213 (which correspond to ananalysis unit according to the invention), a trajectory determinationunit 214 (which corresponds to a determination unit according to theinvention), an image generation unit 215, and an output processing unit216. The sensor information acquisition unit 210, the first imaginaryplane specifying unit 211, the second imaginary plane specifying unit212, the exercise analysis unit 213, the trajectory determination unit214, the image generation unit 215, and the output processing unit 216may be realized by separate calculation units or some or all thereof maybe realized by the same calculation unit.

The control unit 21 may be realized by a computer that includes acentral processing unit (CPU) which is a calculation device, a randomaccess memory (RAM) which is a volatile storage device, a ROM which is anon-volatile storage device, an interface (I/F) circuit connecting thecontrol unit 21 to the other units, and a bus mutually connecting theseunits. The computer may include various dedicated processing circuitssuch as image processing circuits. The control unit 21 may also berealized by an application specific integrated circuit (ASIC) or thelike.

The sensor information acquisition unit 210 receives the packet datareceived from the sensor unit 10 by the communication unit 22 andacquires the time information and the measurement data from the receivedpacket data. The sensor information acquisition unit 210 stores theacquired time information and measurement data in the storage unit 24 inassociation therewith.

The first imaginary plane specifying unit 211 performs a process ofspecifying the first line segment 51 in the major axis direction(longitudinal direction) of the shaft of the golf club 3 at the time ofstopping of the user 2, using the measurement data output by the sensorunit 10. Further, the first imaginary plane specifying unit 211 performsa process of specifying the shaft plane (first imaginary plane) 30 (seeFIG. 2) including the first line segment 51 and the third line segment52 indicating the hitting target direction.

The first imaginary plane specifying unit 211 may calculate thecoordinates of the position 62 of the grip end of the golf club 3 usingthe measurement data output by the sensor unit 10 and specify the firstline segment 51 based on the coordinates of the position 62 of the gripend. For example, the first imaginary plane specifying unit 211 maycalculate an inclination angle (an inclination relative to thehorizontal plane (the XY plane) or the vertical plane (the XZ plane)) ofthe shaft of the golf club 3, using the acceleration data measured bythe acceleration sensor 13 at the time of stopping of the user 2 (thetime of the address) and specify the first line segment 51 using thecalculated inclination angle and information regarding the length of theshaft included in the club specification information.

The first imaginary plane specifying unit 211 may calculate the width ofthe shaft plane 30 using the length of an arm of the user 2 based on thebody information and the length of the first line segment 51.

The second imaginary plane specifying unit 212 performs a process ofspecifying the second line segment 53 forming a predetermined anglerelative to the first line segment 51 specified by the first imaginaryplane specifying unit 211, using the hitting target direction (the thirdline segment 52) as the rotation axis. Further, the second imaginaryplane specifying unit 212 performs a process of specifying the Hogan'splane (second imaginary plane) 40 (see FIG. 2) including the second linesegment 53 and the third line segment 52.

For example, the second imaginary plane specifying unit 212 performs aprocess of estimating the predetermined position 63 between the head andthe chest of the user 2 at the time of stopping of the user 2 (forexample, on a line segment connecting both shoulders to one another)using the body information and the measurement data output by the sensorunit 10 and specifying the second line segment 53 connecting theestimated predetermined position 63 to the position 62 of the head (blowportion) of the golf club 3. The second imaginary plane specifying unit212 performs a process of specifying the Hogan's plane 40 including thesecond line segment 53 and the third line segment 52.

The second imaginary plane specifying unit 212 may estimate thepredetermined position 63 using the coordinates of the position 62 ofthe grip end calculated by the first imaginary plane specifying unit 211and the length of the arm of the user 2 based on the body information.Alternatively, the second imaginary plane specifying unit 212 maycalculate the coordinates of the position 62 of the grip end of the golfclub 3 using the measurement data output by the sensor unit 10. In thiscase, the first imaginary plane specifying unit 211 may specify theshaft plane 30 using the coordinates of the position 62 of the grip endcalculated by the second imaginary plane specifying unit 212.

The second imaginary plane specifying unit 212 may calculate the widthof the Hogan's plane 40 using the length of the arm of the user 2 basedon the body information and the length of the first line segment 51.

The exercise analysis unit 213 performs a process of analyzing a swingexercise of the user 2 using the measurement data output by the sensorunit 10. Specifically, the exercise analysis unit 213 first calculatesan offset amount included in the measurement data using the measurementdata (the acceleration data and the angular velocity data) at the timeof stopping of the user 2 (the time of the address), which is stored inthe storage unit 24. Next, the exercise analysis unit 213 subtracts theoffset amount from the measurement data after start of a swing, which isstored in the storage unit 24 to correct a bias and calculates theposition and posture of the sensor unit 10 during a swing motion of theuser 2 using the measurement data in which the bias is corrected.

For example, the exercise analysis unit 213 calculates the position(initial position) of the sensor unit 10 at the time of stopping of theuser 2 (the time of the address) in the XYZ coordinate system (globalcoordinate system), using the acceleration data measured by theacceleration sensor 13, the club specification information, and thesensor-mounted position information, integrates the subsequentacceleration data, and chronologically calculates a change in theposition of the sensor unit 10 from the initial position. Since the user2 stops at a predetermined address posture, the X coordinate of theinitial position of the sensor unit 10 is 0. Further, the y axis of thesensor unit 10 is identical to the major axis direction of the shaft ofthe golf club 3, and the acceleration sensor 13 measures only thegravity acceleration at the time of stopping of the user 2. Therefore,the exercise analysis unit 213 can calculate an inclination angle of theshaft (an inclination relative to the horizontal plane (the XY plane) orthe vertical plane (the XZ plane)), using y-axis acceleration data.Then, the exercise analysis unit 213 can calculate the Y and Zcoordinates of the initial position of the sensor unit 10 using theinclination angle of the shaft, the club specification information (thelength of the shaft), and the sensor-mounted position information (thedistance from the grip end) and specify the initial position of thesensor unit 10. Alternatively, the exercise analysis unit 213 maycalculate the coordinates of the initial position of the sensor unit 10using the coordinates of the position 62 of the grip end of the golfclub 3 calculated by the first imaginary plane specifying unit 211 orthe second imaginary plane specifying unit 212 and the sensor-mountedposition information (the distance from the grip end).

The exercise analysis unit 213 calculates the posture (initial posture)of the sensor unit 10 at the time of stopping of the user 2 (the time ofthe address) in the XYZ coordinate system (global coordinate system),using the acceleration data measured by the acceleration sensor 13,performs rotation calculation using the angular velocity data measuredsubsequently by the angular velocity sensor 14, and chronologicallycalculates a change in the posture from the initial posture of thesensor unit 10. The posture of the sensor unit 10 can be expressed by,for example, rotation angles (a roll angle, a pitch angle, and a yawangle) around the X axis, the Y axis, and the Z axis, Eulerian angles,quaternions, or the like. At the time of stopping of the user 2, theacceleration sensor 13 measures only the gravity acceleration.Therefore, the exercise analysis unit 213 can specify an angle formedbetween of each of the x, y, and z axes of the sensor unit 10 and agravity direction using triaxial acceleration data. Since the user 2stops at the predetermined address posture, the y axis of the sensorunit 10 is present on the YZ plane at the time of stopping of the user2. The exercise analysis unit 213 can specify the initial posture of thesensor unit 10.

The control unit 11 of the sensor unit 10 may calculate the offsetamount of the measurement data and correct the bias of the measurementdata or a bias correction function may be embedded in the accelerationsensor 13 and the angular velocity sensor 14. In this case, it is notnecessary to correct the bias of the measurement data by the exerciseanalysis unit 213.

The exercise analysis unit 213 defines an exercise analysis model (adouble pendulum model or the like) in consideration of the bodyinformation (the height (length of the arm) of the user 2), the clubspecification information (the length or the position of the center ofthe shaft), the senor-mounted position information (the distance fromthe grip end), features (rigid body and the like) of the golf club 3,and features of a human body (for example, a joint bending direction isdecided), and then calculate a trajectory of the golf club 3 at a swingof the user 2 using the exercise analysis model and the informationregarding the position and posture of the sensor unit 10.

The exercise analysis unit 213 detects a timing (a timing of impact) atwhich a ball is hit during a period of a swing motion of the user 2,using time information and the measurement data stored in the storageunit 24. For example, the exercise analysis unit 213 calculates acomposite value of the measurement data (the acceleration data or theangular velocity data) output by the sensor unit 10 and specifies atiming (time) at which the user 2 hits the ball based on the compositevalue.

Using the exercise analysis model and information regarding the positionand posture of the sensor unit 10, the exercise analysis unit 213 maygenerate a rhythm of a swing from a backswing to follow-through, a headspeed, an incident angle (club pass) or a face angle at the time ofhitting, shaft rotation (a change amount of face angle during a swing),information regarding a deceleration rate or the like of the golf club3, or information regarding a variation in each piece of informationwhen the user 2 performs the swing a plurality of times.

The trajectory determination unit 214 determines whether the trajectoryof the golf club 3 calculated by the exercise analysis unit 213 passesthrough a V zone (a region between the shaft plane 30 specified by thefirst imaginary plane specifying unit 211 and the Hogan's plane 40specified by the second imaginary plane specifying unit 212).Specifically, the trajectory determination unit 214 determines a portionof the trajectory of the golf club 3 which is calculated by the exerciseanalysis unit 213 and passes through the V zone and a portion of thetrajectory which does not pass the V zone.

The image generation unit 215 performs a process of generating imagedata corresponding to an image of an exercise analysis result displayedon the display unit 25. In particular, in the embodiment, the imagegeneration unit 215 generates image data in which a display form of thetrajectory of the golf club 3 is changed in the portion of thetrajectory of the golf club 3 which is determined by the trajectorydetermination unit 214 and passes through the V zone and the portion ofthe trajectory of the golf club 3 which does not pass the V zone. Forexample, the image generation unit 215 generates the image data in whichthe color of the trajectory is changed in the portion of the trajectoryof the golf club 3 which passes through the V zone and in the portion ofthe trajectory of the golf club 3 which does not pass through the Vzone. Specifically, the image generation unit 215 generates the imagedata in which a first color is set to the trajectory of the golf club 3in the portion of the trajectory of the golf club 3 which passes outsidethe V zone and a second color different from the first color is set tothe trajectory in the portion of the trajectory of the golf club 3 whichpasses through the V zone.

The first imaginary plane specifying unit 211, the second imaginaryplane specifying unit 212, the exercise analysis unit 213, thetrajectory determination unit 214, and the image generation unit 215also perform a process of storing various kinds of calculatedinformation in the storage unit 24.

The output processing unit 216 performs a process of causing the displayunit 25 to display various images (including not only an imagecorresponding to the image data generated by the image generation unit215 but also text, signs or the like). For example, the outputprocessing unit 216 causes the display unit 25 to display the imagecorresponding to the image data generated by the image generation unit215 automatically or according to an input operation of the user 2 aftera swing motion of the user 2 ends. Alternatively, the sensor unit 10 mayinclude a display unit, the output processing unit 216 may transmit theimage data to the sensor unit 10 via the communication unit 22, andvarious images may be displayed on the display unit of the sensor unit10.

The output processing unit 216 performs a process of causing the soundoutput unit 26 to output various kinds of audio (also including sound,buzzer tone or the like). For example, the output processing unit 216reads various kinds of information stored in the storage unit 24 andcauses the sound output unit 26 to output audio or sound for exerciseanalysis automatically or at the time of performing a predeterminedinput operation after a swing motion of the user 2 ends. Alternatively,the sensor unit 10 may include a sound output unit, the outputprocessing unit 216 may transmit various kinds of audio data or sounddata to the sensor unit 10 via the communication unit 22, and the soundoutput unit of the sensor unit 10 may be caused to output the variouskinds of audio or sound.

The exercise analysis device 20 or the sensor unit 10 may include avibration mechanism and various kinds of information may be convertedinto vibration information by the vibration mechanism to be presented tothe user 2.

FIG. 4 is a flowchart illustrating an example of an exercise analysisprocess. The control unit 21 executes an exercise analysis programstored in the storage unit 24 to perform the exercise analysis processin the procedure of the flowchart illustrated in FIG. 4.

First, the sensor information acquisition unit 210 acquires themeasurement data of the sensor unit 10 (step S10). When the control unit21 acquires the first measurement data in a swing motion (also includinga stopping motion) of the user 2, the control unit 21 may performprocesses subsequent to step S20 in real time. Alternatively, after thecontrol unit 21 acquires some or all of the series of measurement datain the swing motion of the user 2 from the sensor unit 10, the controlunit 21 may perform the processes subsequent to step S20.

Next, the exercise analysis unit 213 detects a stopping motion (addressmotion) of the user 2 using the measurement data acquired from thesensor unit 10 (step S20). When the control unit 21 performs the processin real time and detects the stopping motion (address motion), forexample, the control unit 21 outputs a predetermined image or audio.Alternatively, the sensor unit 10 may include a light-emitting diode(LED) and blinks the LED to notify the user 2 that the stopped state isdetected so that the user 2 confirms the notification and subsequentlystarts a swing.

Next, the first imaginary plane specifying unit 211 specifies the shaftplane 30 (the first imaginary plane) using the measurement data (themeasurement data in the stopping motion (address motion) of the user 2)acquired from the sensor unit 10 and the club specification information(step S30).

Next, the second imaginary plane specifying unit 212 specifies theHogan's plane 40 (the second imaginary plane) using the measurement data(the measurement data in the stopping motion (address motion) of theuser 2) acquired from the sensor unit 10 and the body information (stepS40).

Next, the exercise analysis unit 213 calculates the initial position andthe initial posture of the sensor unit 10 using the measurement data(the measurement data in the stopping motion (address motion) of theuser 2) acquired from the sensor unit 10 (step S50).

Next, the exercise analysis unit 213 detects a series of motions(rhythm) from the start of the swing to the end of the swing using themeasurement data acquired from the sensor unit 10 (step S60).

The exercise analysis unit 213 calculates the position and posture ofthe sensor unit 10 during the swing motion of the user 2 concurrentlywith the process of step S60 (step S70).

Next, the exercise analysis unit 213 calculates the trajectory of thegolf club 3 during the swing motion of the user 2 using the rhythmdetected in step S60 and the position and posture of the sensor unit 10calculated in step S70 (step S80).

Next, the trajectory determination unit 214 determines whether thetrajectory of the golf club 3 calculated in step S80 passes through theV zone (the region between the shaft plane 30 specified in step S30 andthe Hogan's plane 40 specified in step S40) (step S90). Specifically,the trajectory determination unit 214 determines the portion of thetrajectory of the golf club 3 which is calculated by the exerciseanalysis unit 213 and passes through the V zone and the portion of thetrajectory which does not pass through the V zone.

Next, the image generation unit 215 generates the image data includingthe trajectory of the golf club 3 based on the determination result ofstep S90 (step S100). At this time, the image generation unit 215 doesnot include images of the shaft plane 30 and the Hogan's plane 40 in theimage data and generates the image data in which the display form of thetrajectory of the golf club 3 is changed according to a passage state ofthe trajectory of the golf club 3 through the V zone. For example, theimage generation unit 215 generates the image data in which the color ofthe trajectory is changed in the portion of the trajectory of the golfclub 3 which passes through the V zone and the portion of the trajectorywhich does not pass through the V zone.

The image data generated by the image generation unit 215 is output tothe display unit 25 by the output processing unit 216. Then, the controlunit 21 ends the process of the flowchart illustrated in FIG. 4.

In the flowchart of FIG. 4, the sequence of the processes may beappropriately changed within a possible range.

Next, an example of the process (the process of step S30 in FIG. 4) ofspecifying the shaft plane (the first imaginary plane) will be describedin detail.

As illustrated in FIG. 2, the first imaginary plane specifying unit 211first calculates the coordinates (0, G_(Y), G_(Z)) of the position 62 ofthe grip end based on the acceleration data at the time of the stoppingmeasured by the sensor unit 10 and the club specification information byusing the position 61 of the head of the golf club 3 as the origin O (0,0, 0) of the XYZ coordinate system (global coordinate system). FIG. 5 isa plan view illustrating the golf club 3 and the sensor unit 10 at thetime of stopping of the user 2 (the time of the address) when viewedfrom the negative side of the X axis. In FIG. 5, the position 61 of thehead of the golf club 3 is the origin O (0, 0, 0) and the coordinates ofthe position 62 of the grip end are (0, G_(Y), G_(Z)). Since the gravityacceleration G is applied to the sensor unit 10 at the time of stoppingof the user 2, a relation between the y axis acceleration y(0) and aninclination angle (an angle formed by the major axis of the shaft andthe horizontal plane (XY plane)) a of the shaft of the golf club 3 isexpressed in equation (1).

y(0)=G·sin α  (1)

Accordingly, when L₁ is the length of the shaft of the golf club 3included in the club specification information, G_(Y) and G_(Z) arecalculated using the length L₁ and the inclination angle α of the shaftin equations (2) and (3), respectively.

G _(Y) =L ₁·cos α  (2)

G _(Z) =L ₁·sin α  (3)

Next, the first imaginary plane specifying unit 211 multiplies thecoordinates (0, G_(Y), G_(Z)) of the position 62 of the grip end of thegolf club 3 by a scale factor S to calculate the coordinates (0, S_(Y),S_(Z)) of a midpoint S3 of the vertexes S1 and S2 of the shaft plane 30.That is, S_(Y) and S_(Z) are calculated using equations (4) and (5).

S _(Y) =G _(Y) ·S  (4)

S _(Z) =G _(Z) ·S  (5)

FIG. 6 is a diagram illustrating a cross section obtained by cutting theshaft plane 30 in FIG. 2 along the YZ plane when viewed from thenegative side of the X axis. The length (the width of the shaft plane 30in a direction perpendicular to the X axis) of a line segment connectingthe origin O to the midpoint S3 of the vertexes S1 and S2 is S times thelength L₁ of the first line segment 51. The scale factor S is set to avalue so that the trajectory of the golf club 3 during the swing motionof the user 2 falls within the shaft plane 30. For example, when L₂ isthe length of an arm of the user 2, the scale factor S may be set as inequation (6) so that a width S×L₁ in the direction perpendicular to theX axis of the shaft plane 30 is twice a sum of the length L₁ of theshaft and the length L₂ of the arm.

$\begin{matrix}{S = \frac{2 \cdot \left( {L_{1} + L_{2}} \right)}{L_{1}}} & (6)\end{matrix}$

The length L₂ of the arm of the user 2 has correlation with a height L₀of the user 2. For example, based on statistical information, acorrelation equation as in equation (7) is expressed when the user 2 ismale, and a correlation equation as in equation (8) is expressed whenthe user 2 is female.

L ₂=0.41×L ₀−45.5 [mm]  (7)

L ₂=0.46×L ₀−126.9 [mm]  (8)

Accordingly, the length L₂ of the arm of the user is calculated byequation (7) or (8) using the height L₀ and sex of the user 2 includedin the body information.

Next, the first imaginary plane specifying unit 211 calculates thecoordinates (−TL/2, 0, 0) of the vertex T1, the coordinates (TL/2, 0, 0)of the vertex T2, the coordinates (−TL/2, S_(Y), S_(Z)) of the vertexS1, and the coordinates (TL/2, S_(Y), S_(Z)) of the S2 of the shaftplane 30 using the coordinates (0, S_(Y), S_(Z)) of the midpoint S3calculated as described above and the width (the length of the thirdline segment 52) TL of the shaft plane 30 in the X axis direction. Thewidth TL in the X axis direction is set to a value so that thetrajectory of the golf club 3 during the swing motion of the user 2falls within the shaft plane 30. For example, the width TL in the X axisdirection may be set to be the same as the width S×L₁ in the directionperpendicular to the X axis, that is, twice the sum of the length L₁ ofthe shaft and the length L₂ of the arm.

The shaft plane 30 is specified based on the coordinates of the fourvertexes T1, T2, S1, and S2 calculated in this way.

Next, an example of the process (the process of step S40 in FIG. 4) ofspecifying the Hogan's plane (the second imaginary plane) will bedescribed in detail.

First, the second imaginary plane specifying unit 212 estimates thepredetermined position 63 on the line segment connecting both shouldersof the user 2 to one another to calculate the coordinates (A_(X), A_(Y),A_(Z)), using the coordinates (0, G_(Y), G_(Z)) of the position 62 ofthe grip end of the golf club 3 calculated as described above and thebody information of the user 2.

FIG. 7 is a diagram illustrating a cross section obtained by cutting theHogan's plane 40 in FIG. 2 along the YZ plane when viewed from thenegative side of the X axis. In FIG. 7, the midpoint of the line segmentconnecting both shoulders of the user 2 to one another is set as thepredetermined position 63, and the predetermined position 63 is presenton the YZ plane. Accordingly, the X coordinate A_(X) of thepredetermined position 63 is 0. Then, the second imaginary planespecifying unit 212 estimates that a position obtained by moving theposition 62 of the grip end of the golf club 3 by the length L₂ of thearm of the user 2 in the positive direction of the Z axis is thepredetermined position 63. Accordingly, the Y coordinate A_(Y) of thepredetermined position 63 is the same as the Y coordinate G_(Y) of theposition 62 of the grip end, and the Z coordinate A_(Z) of thepredetermined position 63 is calculated as a sum of the Z coordinateG_(Z) of the position 62 of the grip end and the length L₂ of the arm ofthe user 2, as in equation (9).

A _(Z) =G _(Z) +L ₂  (9)

The length L₂ of the arm of the user is calculated in equation (7) or(8) using the height L₀ and sex of the user 2 included in the bodyinformation.

Next, the second imaginary plane specifying unit 212 multiples the Ycoordinate A_(Y) and the Z coordinate A_(Z) of the predeterminedposition 63 by a scale factor H to calculate the coordinates (0, H_(Y),H_(Z)) of a midpoint H3 of the vertexes H1 and H2 of the Hogan's plane40. That is, H_(Y) and H_(Z) are calculated using equations (10) and(11).

H _(Y) =A _(Y) ·H  (10)

H _(Z) =A _(Z) ·H  (11)

As illustrated in FIG. 7, a length (a width of the Hogan's plane 40 in adirection perpendicular to the X axis) of a line segment connecting theorigin O to the midpoint H3 of the vertexes H1 and H2 is H times thelength L₃ of the second line segment 53. The scale factor H is set to avalue so that the trajectory of the golf club 3 during the swing motionof the user 2 falls within the Hogan's plane 40. For example, theHogan's plane 40 may have the same shape and size as the shaft plane 30.In this case, since a width H×L₃ of the Hogan's plane 40 in thedirection perpendicular to the X axis is identical to the width S×L₁ ofthe shaft plane 30 in the direction perpendicular to the X axis and istwice the sum of the length L₁ of the shaft of the golf club 3 and thelength L₂ of the arm of the user 2, the scale factor H may be set as inequation (12).

$\begin{matrix}{H = \frac{2 \cdot \left( {L_{1} + L_{2}} \right)}{L_{3}}} & (12)\end{matrix}$

The length L₃ of the second line segment 53 is calculated from equation(13) using the Y coordinate A_(Y) and the Z coordinate A_(Z) of thepredetermined position 63.

L ₃=√{square root over (A _(Y) ² A _(Z) ²)}  (13)

Next, the second imaginary plane specifying unit 212 calculates thecoordinates (−TL/2, 0, 0) of the vertex T1, the coordinates (TL/2, 0, 0)of the vertex T2, the coordinates (−TL/2, H_(Y), H_(Z)) of the vertexH1, and the coordinates (TL/2, H_(Y), H_(Z)) of the H2 of the Hogan'splane 40 using the coordinates (0, H_(Y), H_(Z)) of the midpoint H3calculated as described above and the width (the length of the thirdline segment 52) TL of the Hogan's plane 40 in the X axis direction. Thewidth TL in the X axis direction is set to a value so that thetrajectory of the golf club 3 during the swing motion of the user 2falls within the Hogan's plane 40. In the embodiment, the width TL ofthe Hogan's plane 40 in the X axis direction may be set to be the sameas the width of the shaft plane 30 in the X axis direction, and thus maybe set to be twice the sum of the length L₁ of the shaft and the lengthL₂ of the arm, as described above.

The Hogan's plane 40 is specified based on the coordinates of the fourvertexes T1, T2, H1, and H2 calculated in this way.

Next, an example of the process (the process of step S60 in FIG. 4) ofdetecting a timing at which the user 2 hits a ball will be described indetail.

The exercise analysis unit 213 detects a series of motions (alsoreferred to as a rhythm) from the start of the swing to the end of theswing, for example, the start of the swing, a backswing, a top, adownswing, an impact, follow-through, and the end of the swing, usingthe measurement data acquired from the sensor unit 10. A specific rhythmdetection procedure is not particularly limited. For example, thefollowing procedure can be adopted.

First, the exercise analysis unit 213 calculates a sum (referred to as anorm) of the magnitudes of the angular velocities around the axes ateach time t using the acquired angular velocity data of each time t. Theexercise analysis unit 213 may integrate the norm of the angularvelocities at each time t by time.

Here, a case of a graph in which angular velocities around three axes(x, y, and z axes) are shown, for example, in FIG. 8 (which is a diagramillustrating examples of angular velocities output from the sensor unit)will be considered. In FIG. 8, the horizontal axis represents a time(msec) and the vertical axis represents an angular velocity (dps). Thenorm of the angular velocities is shown in the graph illustrated in, forexample, FIG. 9 (which is a diagram illustrating an example of the normof the angular velocities). In FIG. 9, the horizontal axis represents atime (msec) and the vertical axis represents the norm of the angularvelocities. A differential value of the norm of the angular velocity isshown in a graph illustrated in, for example, FIG. 10 (which is adiagram illustrating an example of the differential value of the norm ofthe angular velocity). In FIG. 10, the horizontal axis represents a time(msec) and the vertical axis represents the differential value of thenorm of the angular velocity. FIGS. 8 to 10 are exemplified tofacilitate understanding of the embodiment and do not show accuratevalues.

The exercise analysis unit 213 detects a timing of an impact in theswing using the calculated norm of the angular velocities. For example,the exercise analysis unit 213 detects a timing at which the norm of theangular velocities is the maximum as the timing of the impact (T5 inFIG. 9). For example, the exercise analysis unit 213 may detect a formertiming between timings at which the value of the differential of thecalculated norm of the angular velocities is the maximum and the minimumas the timing of the impact (T5 in FIG. 10).

For example, the exercise analysis unit 213 detects a timing at whichthe calculated norm of the angular velocities is the minimum before theimpact as a timing of a top of the swing (T3 in FIG. 9). For example,the exercise analysis unit 213 specifies a period in which the norm ofthe angular velocities is continuously equal to or less than a firstthreshold value before the impact, as a top period (which is anaccumulation period at the top) (T2 to T4 in FIG. 9).

For example, the exercise analysis unit 213 detects a timing at whichthe norm of the angular velocities is equal to or less than a secondthreshold value before the top, as a timing of the start of the swing(T1 in FIG. 9).

For example, the exercise analysis unit 213 detects a timing at whichthe norm of the angular velocities is the minimum after the impact, as atiming of the end (finish) of the swing (T7 in FIG. 9). For example, theexercise analysis unit 213 may detect a first timing at which the normof the angular velocities is equal to or less than the third thresholdvalue after the impact, as the timing of the end (finish) of the swing.For example, the exercise analysis unit 213 specifies a period in whichthe norm of the angular velocities is continuously equal to or less thana fourth threshold value after the timing of the impact and close to thetiming of the impact, as a finish period (T6 to T8 in FIG. 9).

In this way, the exercise analysis unit 213 can detect the rhythm of theswing. The exercise analysis unit 213 can specify each period (forexample, a backswing period from the start of the swing to the start ofthe top, a downswing period from the end of the top to the impact, and afollow-through period from the impact to the end of the swing) duringthe swing by detecting the rhythm.

Hereinafter, the trajectory determination unit 214 and the imagegeneration unit 215 will be described in detail.

FIG. 11 is a diagram (a diagram projected to the YZ plane) illustratingthe shaft plane and the Hogan's plane when viewed from the negative sideof the X axis. In FIG. 11, the shaft plane 30, the Hogan's plane 40, anda trajectory 3 a of the golf club 3 are illustrated. The trajectory 3 aindicated by a dotted line of FIG. 11 is a trajectory of the golf club 3in a backswing and the trajectory 3 a indicated by a one-dot chain lineis a trajectory of the golf club 3 in a downswing.

The trajectory determination unit 214 divides a space defined with theXYZ coordinate system (global coordinate system) into predeterminedregions. For example, the trajectory determination unit 214 divides thespace into a region (a V zone 71 indicated by diagonal lines in FIG. 11)interposed between the shaft plane 30 specified by the first imaginaryplane specifying unit 211 and the Hogan's plane 40 specified by thesecond imaginary plane specifying unit 212 and the other region. Thetrajectory determination unit 214 determines whether the trajectory 3 aof the golf club 3 calculated by the exercise analysis unit 213 passesthrough the V zone 71. Specifically, the trajectory determination unit214 determines a portion in which the trajectory 3 a of the golf club 3passes through the V zone 71 and a portion in which the trajectory 3 aof the golf club 3 does not pass through the V zone 71.

For example, in the case of FIG. 11, the trajectory 3 a of a portionindicated by ranges A1 and A2 does not pass through the V zone 71 andthe trajectory 3 a of a portion out of the ranges A1 and A2 passesthrough the V zone 71. Accordingly, in the case of FIG. 11, thetrajectory determination unit 214 determines that the trajectory 3 a ofthe portion indicated by the ranges A1 and A2 does not pass through theV zone 71 and determines that the trajectory 3 a of the portion out ofthe ranges A1 and A2 passes through the V zone 71.

When the image generation unit 215 generates the image data of thetrajectory 3 a of the golf club 3, the image generation unit 215 changesa display form of the trajectory 3 a of the golf club 3 based on thedetermination result of the trajectory determination unit 214. Forexample, the image generation unit 215 generates image data in which thetrajectory 3 a inside the V zone 71 (the trajectory 3 a indicated by adotted line and the trajectory 3 a indicated by a one-dot chain lineinside the V zone 71) is set with blue. For example, the imagegeneration unit 215 generates image data in which the trajectory 3 aindicated by the ranges A1 and A2 outside the V zone 71 is set with red.

FIG. 12 is a diagram illustrating an example of a screen displayed on adisplay unit. The image data generated by the image generation unit 215is output to the display unit 25 by the output processing unit 216. Ascreen 80 illustrated in FIG. 12 is a screen example displayed on thedisplay unit 25. The screen 80 is a screen example viewed from the rearside in the hitting direction.

In the screen 80, the trajectory 3 a of the golf club 3 is displayedwithout displaying the V zone. Whether the trajectory 3 a of the golfclub 3 enters the V zone is indicated by the color of the trajectory 3a.

For example, trajectories 3 aa and 3 ac indicated by thick linesrepresent trajectories outside the V zone in a backswing (for example,see the ranges A1 and A2 in FIG. 11) and are indicated with red.Trajectories 3 ab and 3 ad indicated by thin lines representtrajectories inside the V zone in the backswing and are indicated with,for example, blue.

For example, a trajectory 3 ae indicated by a thin line represents atrajectory inside the V zone in a downswing and is indicated with blue.A trajectory 3 af indicated by a thick line represents a trajectoryoutside the V zone in the downswing (for example, see the range A2 inFIG. 11) and is indicated with, for example, red.

Thus, the user 2 can know which portion of his or her swing is deviatedor not deviated from the V zone. For example, when the trajectory 3 a isdisplayed with the colors of the foregoing example, the user 2 canrecognize his or her swing is deviated from the V zone in the redtrajectories 3 aa, 3 ac, and 3 af.

In order to clarify a difference between the trajectories 3 ab, 3 ad,and 3 ae inside the V zone and the trajectories 3 aa, 3 ac, and 3 afoutside the V zone in FIG. 12, the trajectories 3 aa, 3 ac, and 3 afoutside the V zone are indicated by the thick lines, but may bedisplayed with solid lines with the same thickness as the trajectories 3ab, 3 ad, and 3 ae inside the V zone.

The screen 80 illustrated in FIG. 12 may be a 3-dimensional image ofwhich a display angle (viewpoint at which an image is viewed) can bechanged according to an operation of the user 2.

FIG. 13 is a flowchart illustrating an example of operations of thetrajectory determination unit and the image generation unit. Theflowchart of FIG. 13 is a flowchart illustrating the detailed processesof steps S90 and S100 of FIG. 4.

First, the trajectory determination unit 214 specifies the V zone basedon the shaft plane 30 specified in step S30 of FIG. 4 and the Hogan'splane 40 specified in step S40 of FIG. 4 (step S901).

Next, the trajectory determination unit 214 determines whether thetrajectory of the golf club 3 calculated in step S80 of FIG. 4 is insidethe V zone specified in step S901 (step S902). For example, thetrajectory determination unit 214 determines whether the trajectory ofthe golf club 3 is inside the V zone specified in step S901, forexample, in order from an address position to impact.

When the trajectory determination unit 214 determines in step S902 thatthe trajectory of the golf club 3 is inside the V zone (“Yes” in S902),the image generation unit 215 generates image data in which a firstcolor is set to the trajectory of the golf club 3 (step S903). That is,the image generation unit 215 generates the image data in which thefirst color is set to the trajectory of the golf club 3 inside the Vzone. When the image generation unit 215 generates the image data inwhich the first color is set to the trajectory, the process proceeds tostep S905.

When the trajectory determination unit 214 determines in step S902 thatthe trajectory of the golf club 3 is not inside the V zone (“No” inS902), the image generation unit 215 generates image data in which asecond color is set to the trajectory of the golf club 3 (step S904).That is, the image generation unit 215 generates the image data in whichthe second color is set to the trajectory of the golf club 3 outside theV zone. When the image generation unit 215 generates the image data inwhich the second color is set to the trajectory, the process proceeds tostep S905.

The image generation unit 215 determines whether the processes from stepS902 to step S904 are performed from the address of the trajectory ofthe golf club 3 to the impact (step S905). That is, the image generationunit 215 determines whether to generate the image data in which thetrajectory from the address to the impact is subjected to a coloringprocess. When the image generation unit 215 determines that thetrajectory from the address to the impact is not subjected to thecoloring process (“No” in S905), the process proceeds to step S902. Whenthe image generation unit 215 determines that the trajectory from theaddress to the impact is subjected to the coloring process (“Yes” inS905), the process proceeds to step S906.

When the image generation unit 215 determines in step S905 that thetrajectory from the address to the impact is subjected to the coloringprocess (“Yes” in S905), the generated image data is output to theoutput processing unit 216 (step S906).

Thus, for example, the screen 80 described in FIG. 12 is displayed onthe display unit 25. For example, the first color is set to thetrajectories 3 aa, 3 ac, and 3 af indicated by the thick lines in FIG.12 and the second color is set to the trajectories 3 ab, 3 ad, and 3 aeindicated by the thin lines. Accordingly, the user 2 can confirm whetherthe trajectory 3 a of the golf club 3 enters the V zone in the screen80, and thus can simply performs swing estimation of the golf club 3.

As described above, when the trajectory of the golf club 3 is inside theV zone, the first color (for example, red) is set to the trajectory ofthe golf club 3. When the trajectory of the golf club 3 is outside the Vzone, the second color (for example, blue) is set to the trajectory ofthe golf club 3. However, the color of the trajectory of the golf club 3may be changed according to whether a swing is a backswing or adownswing.

For example, the image generation unit 215 generates image data in whicha first color (for example, red) is set to a trajectory outside a V zonein a backswing and a second color (for example, purple) is set to atrajectory outside a V zone in a downswing. Further, the imagegeneration unit 215 generates image data in which a third color (forexample, blue) is set to the trajectory inside the V zone in thebackswing and a fourth color (for example, black) is set to thetrajectory inside the V zone in the downswing.

In this case, for example, the first color (for example, red) is set tothe trajectories 3 aa and 3 ac (trajectories outside the V zone in thebackswing) in FIG. 12 and the second color (for example, purple) is setto the trajectory 3 af (a trajectory outside the V zone in thedownswing). Further, the third color (for example, blue) is set to thetrajectories 3 ab and 3 ad (trajectories inside the V zone in thebackswing) in FIG. 12 and the fourth color (for example, black) is setto the trajectory 3 ae (a trajectory inside the V zone in thedownswing).

Thus, the user 2 can recognize whether the trajectory 3 a of the golfclub 3 is deviated from the V zone in the backswing and is deviated fromthe V zone in the downswing, and thus can simply perform a swingestimation of the golf club 3.

As described above, the exercise analysis device 20 determines that thetrajectory of the golf club 3 passes through the V zone. Thus, theexercise analysis device 20 can change a display form of the trajectoryaccording to a passage state of the trajectory of the golf club 3. Thus,the user 2 can easily see which portion of the trajectory of the golfclub 3 passes through the V zone and can simply perform the swingestimation of the golf club 3.

Since the exercise analysis device 20 specifies the shaft plane 30 andthe Hogan's plane 40 using the sensor unit 10, it is not necessary touse a large-scale device such as a camera and restriction on a placewhere the type of swing is estimated is small.

As described above, the image generation unit 215 generates the imagedata in which the color of the trajectory is changed between the portionof the trajectory of the golf club 3 which passes through the V zone andthe portion of the trajectory of the golf club 3 which does not passthrough the V zone, but may generate the image data so that thetrajectory continuously lights and the trajectory blinks. For example,the image generation unit 215 may generate the image data so that thetrajectory inside the V zone continuously lights and the trajectoryoutside the V zone blinks.

The image generation unit 215 may generate the image data in which kindsof lines of the trajectories of the golf club 3 are changed. Forexample, the image generation unit 215 may generate the image data inwhich the trajectory inside the V zone is displayed with a solid lineand the trajectory outside the V zone is displayed with a dotted line ora broken line.

The image generation unit 215 may generate the image data in which thethicknesses of the lines of the trajectories of the golf club 3 arechanged. For example, the image generation unit 215 may generate theimage data so that the trajectory inside the V zone is displayed with athin line and the trajectory outside the V zone is displayed with athick line.

The image generation unit 215 may generate the image data so that thetrajectory inside the V zone is not displayed and only the trajectoryoutside the V zone is displayed.

The image generation unit 215 may generate the image data in which firstand second regions interposing a V zone are defined outside the V zone,and the V zone and the first and second regions are distinguished anddisplayed.

The image generation unit 215 may generate the image data in whichpredetermined colors are set to a region opposite to the V zoneincluding the shaft plane 30 and a region opposite to the V zoneincluding the Hogan's plane 40. For example, the image generation unit215 may generate the image data in which the predetermined colors areset to a first region outside the V zone and present counterclockwisefrom the shaft plane 30 and a second region outside the V zone andpresent clockwise from the Hogan's plane 40 in FIG. 11. At this time,the image generation unit 215 may include information indicating thatthe first region is a slice zone and the second region is a hook zone inthe image data. Thus, the user 2 can recognize whether his or her swingtendency is a slice tendency or a hook tendency.

The image generation unit 215 may change a display form of thetrajectory in a rhythm of a predetermined section. For example, in FIG.13, the image generation unit 215 changes the display form of thetrajectory from the address to the impact, but may change the displayform of a trajectory from the address to the end of a swing. The imagegeneration unit 215 may change the display form of the trajectory inregard to a trajectory of only a downswing.

The image generation unit 215 may generate the image data in which the Vzone is colored. For example, the image generation unit 215 may generatethe image data in which a region interposed between the shaft plane 30and the Hogan's plane 40 is all painted with a predetermined color. Inthis case, the image generation unit 215 may display a trajectory ofwhich the above-described display form is changed in the image data inwhich the V zone is colored. The image generation unit 215 may displaythe trajectory without changing the display form according to whetherthe trajectory is inside or outside the V zone (for example, thetrajectory may be displayed with one color).

The image generation unit 215 may generate the image data which includesa region outside a V zone including a line segment obtained bymultiplying the first line segment 51 by the scale factor S and theHogan's plane 40.

FIG. 14 is a diagram illustrating an example of a screen in which aregion outside a V zone including a line segment and a Hogan's plane isdisplayed. As illustrated in FIG. 14, a line segment 91 obtained bymultiplying the first line segment 51 by the scale factor S is displayedin a screen 90. A region 92 outside a V zone including the Hogan's plane40 as a part of a side surface is displayed in the screen 90. The region92 is all painted with a predetermined color.

The image generation unit 215 may indicate the V zone by the linesegment 91 and the region 92, as illustrated in FIG. 14. As describedabove, the image generation unit 215 displays a trajectory of which adisplay form is changed according to whether the trajectory is inside oroutside the V zone.

The image generation unit 215 may display the first line segment 51 inthe screen 90 instead of the line segment 91. The image generation unit215 may generate the image data which includes a region outside a V zoneincluding a line segment obtained by multiplying the second line segment53 by the scale factor H and the shaft plane 30.

As described above, the second imaginary plane specifying unit 212specifies the second line segment 53 using the body information and themeasurement data output by the sensor unit 10. However, a process ofspecifying the second line segment 53 connecting the positions 63 and 62of the head (the blow portion) of the golf club 3 may be performed usingthe first line segment 51 specified by the first imaginary planespecifying unit 211 and the predetermined angle θ relative to the firstline segment 51.

As described above, the Hogan's plane 40 is specified by the output ofthe sensor unit 10 fitted in the golf club 3, but the invention is notlimited thereto. For example, a sensor unit may be fitted in an arm orthe like of the user 2 and the Hogan's plane 40 may be specified basedon an output of the sensor unit.

As described above, the acceleration sensor 13 and the angular velocitysensor 14 are embedded in the sensor unit 10 to be integrated, but theacceleration sensor 13 and the angular velocity sensor 14 may not beintegrated.

Alternatively, the acceleration sensor 13 and the angular velocitysensor 14 may not be embedded in the sensor unit 10, but may be mounteddirectly on the golf club 3 or the user 2. In the foregoing embodiments,the sensor unit 10 and the exercise analysis device 20 are separated,but the sensor unit 10 and the exercise analysis device 20 may beintegrated to be mounted on the golf club 3 or the user 2.

In the foregoing embodiments, the exercise analysis device 20 calculatesthe Z coordinate A_(Z) of the predetermined position 63 on the linesegment connecting both shoulders of the user 2 to one another as thesum of the Y coordinate G_(Y) of the position 62 of the grip end and thelength L₂ of the arm of the user 2 as in equation (9), but anotherequation may be used. For example, the exercise analysis device 20 maymultiply L₂ by a coefficient K and adds G_(Y) to calculate A_(Z) as inA_(Z)=G_(Y)+K·L₂.

The exercise analysis system (the exercise analysis device) analyzing agolf swing has been exemplified above. However, the invention can beapplied to an exercise analysis system (exercise analysis device)analyzing swings of various exercises of tennis, baseball, and the like.

The functional configuration of the exercise analysis system describedabove is classified according to main processing content in order tofacilitate understanding of the configuration of the exercise analysissystem. The invention is not limited by the method of classifying theconstituent elements or the names of the constituent elements. Theconfiguration of the exercise analysis system can be classified intofurther many constituent elements according to the processing content.One constituent element can be classified to perform more processes. Theprocess of each constituent element may be performed by one piece ofhardware or may be performed by a plurality of pieces of hardware.

Units of processes in the flowcharts described above are dividedaccording to main processing content in order to facilitateunderstanding of the process of the exercise analysis device. Theinvention is not limited by a method of dividing the units of processesor the names of the units of processes. The process of the exerciseanalysis device can be divided in more units of processes according tothe processing content. One unit of process can be divided to includemore processes. The processing procedure of the foregoing flowchart isnot limited to the example illustrated in the drawing.

The embodiments of the invention have been described above, but thetechnical scope of the invention is not limited to the scope describedin the foregoing embodiments. It should be apparent to those skill inthe art that various modifications or improvements of the foregoingembodiments are made. It should be apparent from the description of theappended claims that the modifications or the improvements are alsoincluded in the technical scope of the invention. The invention can alsobe provided as an exercise analysis method, a program for the exerciseanalysis device, or a recording medium storing the program. In theforegoing embodiments, the sensor unit 10 and the exercise analysisdevice 20 have been described as separate elements, but the function ofthe exercise analysis device 20 may be mounted on the sensor unit 10.

The entire disclosure of Japanese Patent Application No. 2014-256579,filed Dec. 18, 2014 is expressly incorporated by reference herein.

What is claimed is:
 1. An exercise analysis device comprising: a firstspecifying unit that specifies a first axis which lies in a longitudinaldirection of a shaft of an exercise tool at an address posture of auser, using an output of an inertial sensor; a second specifying unitthat specifies a second axis forming a predetermined angle along withthe first axis, using a hitting direction as a rotation axis; ananalysis unit that calculates a trajectory of a swing of the user basedon an output of the inertial sensor; and a determination unit thatdetermines whether the trajectory passes through a predetermined regionspecified based on the first and second axes.
 2. The exercise analysisdevice according to claim 1, wherein the determination unit determines aportion of the trajectory which passes through the predetermined regionand a portion of the trajectory which does not pass through thepredetermined region.
 3. The exercise analysis device according to claim2, further comprising: an image generation unit that generates imagedata in which a display form of the trajectory differs between theportion which passes through the predetermined region and the portionwhich does not pass through the predetermined region.
 4. The exerciseanalysis device according to claim 3, wherein the image generation unitgenerates the image data in which a color of the trajectory differsbetween the portion which passes through the predetermined region andthe portion which does not pass through the predetermined region.
 5. Theexercise analysis device according to claim 3, wherein the imagegeneration unit generates the image data in which the trajectorycontinuously lights and blinks to distinguish the portion which passesthrough the predetermined region from the portion which does not passthrough the predetermined region.
 6. The exercise analysis deviceaccording to claim 3, wherein the image generation unit generates theimage data in which a kind of line of the trajectory differs between theportion which passes through the predetermined region and the portionwhich does not pass through the predetermined region.
 7. The exerciseanalysis device according to claim 3, wherein the image generation unitgenerates the image data in which a thickness of a line of thetrajectory differs between the portion which passes through thepredetermined region and the portion which does not pass through thepredetermined region.
 8. The exercise analysis device according to claim1, wherein the first specifying unit specifies a first imaginary planeincluding the first axis and the hitting direction, wherein the secondspecifying unit specifies a second imaginary plane including the secondaxis and the hitting direction, and wherein the predetermined region isa region interposed between the first and second imaginary planes. 9.The exercise analysis device according to claim 8, wherein the imagegeneration unit defines first and second regions interposing thepredetermined region outside the predetermined region, and generatesimage data in which the predetermined region, the first region, and thesecond region are distinguished and displayed.
 10. An exercise analysismethod comprising: specifying a first axis which lies in a longitudinaldirection of a shaft of an exercise tool at an address posture of auser, using an output of an inertial sensor; specifying a second axisforming a predetermined angle along with the first axis, using a hittingdirection as a rotation axis; calculating a trajectory of a swing of theuser based on an output of the inertial sensor; and determining whetherthe trajectory passes through a predetermined region specified based onthe first and second axes.
 11. The exercise analysis method according toclaim 10, wherein in the determining of the trajectory, a portion of thetrajectory which passes through the predetermined region and a portionof the trajectory which does not pass through the predetermined regionare determined.
 12. A program causing a computer to perform: specifyinga first axis which lies in a longitudinal direction of a shaft of anexercise tool at an address posture of a user, using an output of aninertial sensor; specifying a second axis forming a predetermined anglealong with the first axis, using a hitting direction as a rotation axis;calculating a trajectory of a swing of the user based on an output ofthe inertial sensor; and determining whether the trajectory passesthrough a predetermined region specified based on the first and secondaxes.
 13. A recording medium that records a program causing a computerto perform: specifying a first axis which lies in a longitudinaldirection of a shaft of an exercise tool at an address posture of auser, using an output of an inertial sensor; specifying a second axisforming a predetermined angle along with the first axis, using a hittingdirection as a rotation axis; calculating a trajectory of a swing of theuser based on an output of the inertial sensor; and determining whetherthe trajectory passes through a predetermined region specified based onthe first and second axes.
 14. An exercise analysis system comprising:an inertial sensor; a first specifying unit that specifies a first axiswhich lies in a longitudinal direction of a shaft of an exercise tool atan address posture of a user, using an output of the inertial sensor; asecond specifying unit that specifies a second axis forming apredetermined angle along with the first axis, using a hitting directionas a rotation axis; an analysis unit that calculates a trajectory of aswing of the user based on an output of the inertial sensor; and adetermination unit that determines whether the trajectory passes througha predetermined region specified based on the first and second axes. 15.An exercise analysis device that determines whether a trajectory of aswing of a user passes through a V zone.
 16. The exercise analysisdevice according to claim 15, wherein a display form of the trajectorydiffers between a portion of the trajectory which passes through the Vzone and a portion of the trajectory which does not pass through the Vzone.
 17. The exercise analysis device according to claim 16, furthercomprising: an image generation unit that generates image data in whichthe display form of the trajectory differs between the portion whichpasses through the predetermined region and the portion which does notpass through the predetermined region.
 18. The exercise analysis deviceaccording to claim 16, wherein the image generation unit generates imagedata in which a color of the trajectory differs between the portionwhich passes through the predetermined region and the portion which doesnot pass through the predetermined region.
 19. The exercise analysisdevice according to claim 16, wherein the image generation unitgenerates image data in which the trajectory continuously lights andblinks to distinguish the portion which passes through the predeterminedregion from the portion which does not pass through the predeterminedregion.
 20. The exercise analysis device according to claim 16, whereinthe image generation unit generates image data in which a kind of lineof the trajectory differs between the portion which passes through thepredetermined region and the portion which does not pass through thepredetermined region.
 21. The exercise analysis device according toclaim 16, wherein the image generation unit generates image data inwhich a thickness of a line of the trajectory differs between theportion which passes through the predetermined region and the portionwhich does not pass through the predetermined region.